Furnace observation port



Oct. 4, 1966 K. s. SVENDSEN FURNACE OBSERVATION PORT 2 Sheets-$heet 1Filed Feb. 24, 1965 FIG. I

INVENTOR. KONRAD S. SVENIDSEN MiG 140v ATTORNEY Oct. 4, 1966 K. s.SVENDSEN FURNACE OBSERVATION PORT 2 Sheets-Sheet 2 Filed Feb. 24, 1965FIG. 4

FIG. 3

INVENTOR. KONRAD s. SVENDSEN ATTORNEY United States Patent 3,276,442FURNACE OBSERVATION PORT Konrad S. Svendsen, Bloomfield, Conn., assignorto Combustion Engineering, Inc., Windsor, Conn., a corporation ofDelaware Filed Feb. 24, 1965, Ser. No. 434,939 1 Claim. '(Cl. 126--200)This invention relates to passageways or openings in walls ofpressurized furnaces or other chambers under superatmospheric pressure,and particularly to means for maintaining such passageways capable ofbeing seen through at all times.

In many pressurized furnaces it is desirable to provide an opening forthe purpose of observing the inside of the furnace, and to permit accessto the furance for the purpose of cleaning or lancing the furnace walls.A glass window is usually utilized for observation of the furnaceinterior. When a dirty fuel, for example coal, is being burned in thefurnace, difiiculties are encountered in keeping the glass from cloudingor fogging over, and preventing abuildup of ash thereon.

It is an object of the present invention to provide an observation portfor a pressurized furnace which will allow observation of a largeportion of the furnace interior, and to effectively maintain the glassclean and cool at all times, so that visibility will not be restricted.

Other and further objects of the invention will become apparent to thoseskilled in the art as the description proceeds. An illustrativeembodiment of the invention is shown in the accompanying drawingswherein:

FIGURE 1 is a front view of a furnace observation port;

FIGURE 2 is a sectional plan view of the port;

FIGURE 3 is a sectional side view of the furnace port taken along lines3-3 of FIGURE 2; and

FIGURE 4 is a sectional view taken along lines 4-4 of FIGURE 2.

Looking now to FIGURE 1, denotes a furnace observation door for apressurized furnace, which door contains a rectangular glass plate 12therein. The door 10 can be pivoted upwardly about hinge pin 14. Nut 20holds the door securely on hinge 14. On the other side of the door isbolt 22 and its associated threaded hand knob 24, by means of which thedoor can be tightly secured in place, covering the opening or passagewayleading to the furnace interior.

Looking now to FIGURE 2, the entire observation port housing 18 issecured to the furnace wall 16 in any suitable manner, for example bywelding. The housing 18 contains the rectangular passageway 19, whichcommunicates at its inner end with the furnace interior. Retaining ring26 holds the glass plate securely in place in the furnace door. O-ring28 forms a seal between the glass plate and the door. A sealing gasket30, contained in the furnace door, forms a seal between the door and thehousing when the door is in its closed position. The sealing membersshould be made of a suitable heat resistant material, for exampleasbestos.

Air for cleaning and cooling the glass plate is directed into annularchamber 32 by way of pipe 34. High pressure air, to be used for formingan effective screen for passageway 19 when the door is opened, isdirected into annular chamber 38 by means of pipe 40. This air isdischarged into passageway 19 by way of jets 36.

As best seen in FIGURE 3, a plurality of jets 42 discharge the cleaningand cooling air directly onto the surface of the plate glass. Thisprevents ash from collecting thereon, and also keeps it cool, so that itwill not fog or cloud over.

FIGURE 4 illustrates the location of the aspirating jets 36 and the jets42 used for cleaning and cooling "ice the window. As shown, theh jets 36are located on either side of the passageway 19, and the jets 42 arelocated above and below passageway 19. This construction permits housing18 to be made quite compact. Obviously, if the length of passageway 19is increased, the amount of the opposite interior furancewall that canbe observed is decreased.

By making the glass plate and passageway 19 rectangular, and keeping thelength of passageway .19 as short as possible, an observer lookingthrough the window can see a substantial portion of the furnace interiorboth above and below the level of the observation port. This isparticularly advantageous on coal fired furnaces. By looking through theobservation ports, an operator can determine the slag conditions in thefurnace and take corrective action when required.

The operation of the device is as follows. During normal operation ofthe furnace, with door 10 closed, cool air is continuously supplied tojets 42. This air in sweeping across the face of glass 12 maintains itrelatively 0001, thereby preventing it from fogging over. The cool airalso prevents ash particles from accumulating on the surface of theglass. This is particularly a problem when coal is the fuel being burnedin the furnace. The cool air also reduces the problem of heat stressesbeing created in the glass due to temperature differentials.

When it is desired to gain access to the furnace, hand knob 24 isunthreaded, and also nut 20. The door can then be pivoted upwardlyaround hinge pin 14. When the door is opened, high pressure air isdelivered to annular chamber 38, and is discharged into passageway 19through jets 36. These jets of high pressure .air are directed at acommon line of intersection, which is preferably some distance from theinner edge of passageway 19. This forms an effective screen whichprevent hot combustion gasses from escaping through the passageway,which hot gasses could seriously injure an observer if allowed to escapefrom the furnace. When the door is again closed, the high pressure aircan be shut off.

For a passageway approximately 2 wide and 4" high, it has been foundthat the air for forming the protective screen should be approximately65 p.s.i. This forms an effective screen against puffs of combustiongases up to a maximum of 40" water, or approximately 1.5 p.s.i. Thenormal operating pressure of a pressurized furnace is 18" of water aboveatmospheric pressure, or somewhat less than 1 p.s.i. above atmosphericpressure.

The cleaning and cooling air which is continuously directed at the glasswindow need not be under nearly as high a pressure as the aspirating orprotective screen air. All it need be is 1" to 4" W.G. (water gauge)above the operating pressure of the furnace, so that it can bedischarged through the jets 38 with sufficient velocity so as to sweepacross the surface of the glass: plate. Since this cleaning and coolingair is introduced into passageway 19 continuously during operation ofthe furnace, it is economically necessary to keep the pressure of thisfluid down to the absolute minimum.

While I have illustrated and described a preferred embodiment of myinvention, it will be understood that minor changes in construction andarrangement of parts may be made without departing from the spirit andscope of the invention as claimed. It is therefore intended that allmatter contained in the description or shown in the accompanyingdrawings be interpreted as illustrative and not in a limiting sense.

What I claim is:

In a furnace operating under superatmospheric pressure, a passageway,having an inner end and an outer end, extending through one of the wallsof said furnace, a door for closing the outer end of the passageway, aglass window contained in the door, a plurality of first jet meanspositioned along the sides of the passageway, said first jet meanshaving inlets for receiving high pressure gaseous fluid, and outletsopening into the periphery of said passageway, said first jet meansbeing positioned with their outlets closer to the inner end of thepassageway than their inlets, so that they direct streams of gaseousfluid under high pressure into said passageway to form a gaseous screento prevent fluid flow from said furnace out through said passageway whensaid door is removed from the outer end of the passageway, a pluralityof second jet means positioned above and below the pas- :ageway, saidsecond jet means having inlets for receiving oool, pressurized fluid,and outlets opening into the periphery of said passageway, said secondjet means References Cited by the Examiner UNITED STATES PATENTS1,717,637 6/1929 Vastine 12620O 2,850,005 9/1958 Good et a1. 126-2002,988,024 6/1961 Harris 110-179 being positioned with their outletscloser to the outer 15 KENNETH W. SPRAGUE, Primary Examiner.

